In wireless communication systems, a base station (BS) communicates with plural mobile stations (User Equipment: UE) via various multiple access schemes. The multiple access scheme is classified, according to resources to be divided, into the code multiplexing access (CDMA) that executes accessing via code division, the frequency divisional multiplexing access (FDMA) that executes accessing via frequency division, and the time divisional multiplexing access (TDMA) that executes accessing via time division.
The FDMA scheme has gotten a lot of attention because it is effective in high-speed data transmission via wireless channels. As to the FDMA scheme, there is a single-carrier FDMA (SD-FDMA) scheme, which is up-link multiple access adopted in long term evolution (LTE) of 3rd generation partnership project (3GPP), in addition to the orthogonal frequency division multiplexing, which transmits data with plural orthogonal sub-carriers (see non-patent document 1).
The system, which performs communications according to the FDMA scheme, uses orthogonal frequencies to transmit data to different users so that interference between users is suppressed. Mobile stations become various communication states under a wide variety of environments. Flexibly allocating wireless communication resources is important to obtain the multiple diversity effect. For that reason, flexibly allocating wireless communication resource by a base station is effective to obtain a high throughput in the FDMA scheme (see non-patent document 2).
The sub-carrier groups arranged serially on the frequency axis one slot form one resource block (RB). When the bandwidth of a resource block is smaller than the coherent bandwidth of a channel, it can be assumed that the channel frequency response of one resource block is constant.
By allocating resource blocks in good channel state to mobile stations, the base station can obtain a large multiple diversity effect (see non-patent document 3). As a result, high throughput can be realized. Hereinafter, the method will be described below.
For scheduling depending on a propagation path, each mobile station transmits a reference signals and the base station measures the channel quality indicator (CQI) using the transmitted reference signal and then inputs the CQI to the scheduler unit.
Plural resource block groups, formed of resource blocks in serial on the frequency axis at one transmission time interval (TTI), are allocated to mobile stations UE based on the CQI order of a mobile station in each input resource block. Hereinafter, the resource block group is called as frequency block. The non-patent document 2 describes that scheduling depending on the propagation path in the frequency domain increases the multiple diversity effect. However, the non-patent document 2 does not disclose how to allocate a limited number of plural frequency blocks to mobile stations UE.
Non-patent document 1: 3GPP TR 25.814(V7.1.0), “Physical layer aspects for evolved Universal Terrestrial Radio Access (UTRA)”, “http://www.3gpp.org/ftp/Specs/archive/25_series/25.814/.
Non-patent document 2: W. Rhee and J. M. Cioffi, “Increase in capacity of multi user OFDM system using dynamic subchannel allocation,” Proc. IEEE VTC'00, Tokyo, Japan, May 2000, pp. 1085-1089.
Non-patent document 3: NEC Group, R1-071507, “DL unicast resource allocation signaling”, 3GPP TSG-RAN WG1 Meeting #48bis, St. Julian's, Malta, 26-30 Mar. 2007.